Tests were conducted with two sound-power reference sources (Bruel and
Kjaer model 4204) in three different acoustical environments: half of a
reverberation room (overall room dimensions 6.7x5.5x4.1 m), a large
semi-anechoic room, and an indoor work space. Sound power (narrow band 136--6400
Hz) was determined using a semicircular array of eight sound-intensity probes
rotated in steps of 20 deg (72 measurement positions) over a hemispherical
integration surface, radius 1.52 m, with the source at the center. The floor
base completing the surface enclosing the source was assumed to be rigid with
zero normal intensity. Despite prevailing concerns about sound-intensity
measurement in diffuse fields and reverberant spaces, it was found that there
was quite close agreement between sound power determined in the reverberation
room and sound power determined in the other two environments. Sound power
determined in the semi-anechoic room and work space was found to be highly
repeatable, within 2%. For both sources the sound power was about 10% less than
the manufacturer's calibrated value. With the source outside the integration
surface, sound power determined in the semi-anechoic room was two orders of
magnitude less than sound power with the source inside. [See NOISE-CON
Proceedings for full paper.]